Bought one of these knowing it was suspiciously cheap, but not actually the cheapest of the batteries on offer, thus hoping it might be the real deal.
Found after opening that though it looked very like the old original Nokia battery the 'hologram' did not actually move when flexed in the light. Nevertheless it was better than the clapped-out old genuine Nokia battery. It did not seem to last a terrifically long length of time however: on standby (i.e. not being used to make calls, just being left switched on) it lasts several days (four?). I checked just now to see the original phone spec 'on standby' and it was 340 hours i.e. 14 days. Even allowing for a little exaggeration by Nokia, this battery is not up to spec., nor is it up to the performance of the original.
I am not sure I want to complain to the supplier about this, given its cheapness, but don't be fooled the way I was.